50 Dry Shot Graph
Here is a 50 Dry Shot on a C5
Chart is 3000 RPM Start through 3000 RPM end (yes I learned how to filter)
Showing the ranges of each PID through the filter.
Here is my question, during this part of the run DC was over 100%, what makes the DC exceed 100% (am I logging the cause?)?
I would think the 106% would be in the upper RPM's, not the middle of the nitrous run?
Last edited by Beer99C5; August 19th, 2006 at 10:58 AM.
1999 C5 A-4 Convertible
1 of 245 Nassua Blue 99 Vert's, Blackwing, LS6 Intake, 42 # Injectors, Two Stage Nitrous System- Dry and a Wet Plate, EFI Live Scan/Tune V2, 1999 PCM with 2002 COS 5 OS Custom Nitrous Panel.
Maine USA
The PCM wants to spray more fuel to meet the commanded AFR (obtained/derived from the various tables), so it increases the injector pulse width, if the injector isn't big enough the DC goes over 100%.
The injectors are at maximum flow at 100% (they are being held open).
Looks like you're barely going over 100%, but watch out (for leaness), greater than 100% means the PCM wants more fuel but the injectors can't give any more.
I dont mean to be a smarty pants but DC (duty cycle) is measures as percentage of a crankshaft revolution. So, if your injectors are open 100% this means the crank has turned one complete revolution while the injector is open. Hence, it is quite possible to have over 100% duty (over one revolution). Most manufactures recomend 80% duty max but the end result of over 100% will limit max power and this will not show up on AFRs.Originally Posted by joecar
BTW: the higher your rev the motor, shortens the time you have to open the injectors.
Batman,
Hi there, welcome to the forum...
100% = 2 crank revolutions, that is how it's defined.
Doesn't show up on actual AFR because the injectors are all the way open maxed out.
I'll bet you a box of donuts...
Cheers
Joe
Here is the dyno sheet showing the AFR for the 50 dry shot on my car (vs baseline NA), this was done a month or so before I bought the EFI Scan package.
With the 75 shot the AFR was up to 13.5 (run outta injectors), so I reverted back to the 50.
I am installing the LC-1 (my third one...) and also installing the Fuel Pressure sending unit Friday. Will be doing more logging next week.
Here is the 75 shot dyno...
Last edited by Beer99C5; August 28th, 2006 at 08:23 PM.
1999 C5 A-4 Convertible
1 of 245 Nassua Blue 99 Vert's, Blackwing, LS6 Intake, 42 # Injectors, Two Stage Nitrous System- Dry and a Wet Plate, EFI Live Scan/Tune V2, 1999 PCM with 2002 COS 5 OS Custom Nitrous Panel.
Maine USA
Hmmm, Bumper's.I'll bet you a box of donuts...
Cheers
Joe
It's a lot easier to ask for forgiveness than it is to ask for permission.
Mate, you're really bad...Hmmm, Bumper's.
upgrade injectors or increase fuel pressure, as u wanted to go a 75 shot, and injector duty cycle shouldnt really be going over 85%, this is your only option or run a fuel noz with the nitrous noz.
also is the command air/fuel matching the dyno air/fuel results.
OK I got the 42's in and the AFR is 10.5's now with a duty cycle of 62% for a 75 shot, going up to a 100 next
It was commanding 11.7 and I was getting 10.5, so do I take the PE and try to command it to say 12.7 or so to try and get mid 11's?
Heres the log if anyones wants to see it.
75 Dry shot Log
1999 C5 A-4 Convertible
1 of 245 Nassua Blue 99 Vert's, Blackwing, LS6 Intake, 42 # Injectors, Two Stage Nitrous System- Dry and a Wet Plate, EFI Live Scan/Tune V2, 1999 PCM with 2002 COS 5 OS Custom Nitrous Panel.
Maine USA
no, you get VE done perfect first, so commanded PE should be close to effective one, albait it's never gonna be quite right with the temps changing quickly...
did you do the same experiment in SD yet like we talked about earlier?
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